Projection-lamp.



J. M. NAUL.

PROJECTION LAMP.

APPLICATION mm MAY 1 2. 1915.

Jan. 2, 1917.

Puten ted S m m m H W JAMES MYRVEN N'AUL, OF PLAINFIELD, NEW JERSEY, ASSIGNOR T0 BOSCH MAGNETO COMPNY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROJECTION-LAMI.

Speefication of Letters Patent.

Application filed May 12, 1915. Serial No. 27,698.

T0 all wlwm z' may concem:

Boit known that I, JAMES M. NAUL, a citizen of the United States, residing at and whose post office address is' 747 Kensington avenue, Plainfield, New Jersey, have invented certain new and useful Improvements in Projection-Lamps; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as Will enable others skilled in the art to Which it appertains to make and use the same.

' In projection lamps, the reflecting surfaces are usually of parabolic, spherical or elliptical form, and may be associated with condensers or other lenses and also with supplementary reflectors, the object being to V focal point 'from which the light rays emanating therefrom and striking the reflecting surface are projected in fines parallel to the axis of the lamp, the light rays emanating from all other points of the light-giving medium being projected at an angle thereto. These angulaly projected rays are subtracted from the cylindrical beam and thus reduce its intensity. Those rays Which are directed downwardly may be desirable for illuminating the way directly ahead of the.

vehicle, although the way is usually illuminated toc brilliantly and too close to the Vehicle; and those rays which are directed sidewise and upwardly, usually represent a total loss in the light-giving effectiveness of the lamp. Since it is impossible as a practi cal matter to concentrate the light-giving medium at a single point, even when ah incandescent lampis used for the purpose, these refleotor headlights project a cylindrical beam of reduced intensity and difiused rays which in most part are wasted.

The object of my invention is to produce a forwardly directed beam of light of much intensity, and I do this in a refiector head-' light by providing a refiecting surface which is not generated by a curve in rotation as heretofore, but is formed of curves having foci at slightly separated points which are contained in the light-giving medium. In th1s way, light rays emanating from a plurality of points in the arc, fiame or filament forming the light-gving medium, are projected in a forwardly d1rected beam of cylindrical or other form, while the projected rays outside of the beam may be directed in such manner as to illuminate the way With greater efi'ectiveness.

In the preferred form of my invention for headlights for moving vehicles, I use a reflecting surface formed by parabolas of gradual diflering focal length and.having their-foci wholly contained in an axially arranged filament of an incandescent lamp. T he projection therefrom consists of a comparatively intense, axially-directed, cylindrical beam, and angularly directed rays Which efl'ectively illuminate the way with difl'used light.

It Will be observed that in headlights having the reflecting surface generated by a parabola in rotation on its axis, the rays emanating from the single point of the light at the focus of the parabola are projected in an axially-directed cylindrical beam, while in my preferred form of lamp, all the rays from the entire filament which strike the reflecting surface at the parabolic curves having their foci at the points of emanation go into the axially-directed cylindrical beam.

In the accompanying drawings illustratin-g the preferred embodiment of my invention in application to a reflector headlight of the electric type, especially adapted for moving vehicles as an example, Figure 1 is a vertical section along the axis of the lamp; and Fig. 2 is a front elevation thereof.

The projection lamp shown in the draW- ings has afront cover of glass 1 permanently fastened over the front of the reflector 2 by the retaining rim 3. It also has an incandescent lamr 4 fixed in a socket 5 Which also carries the refiecting portion 6 normally conformi to the contour of the refiector. The terminal connector 7 provides the electrie circuit connection with the filament of the lamp, and the arrangement is such that therefiector 2, together with the incandes- Patented Jan. 2, 1917.

' lengthsof the interrnediate parabolas graduof the headlig t. The filament 9 of the in' v 6 ally vary between these two. Furthermore,

the axes of the parabolas concide with the axis 0f the headlight. lhus, the focus of the parabolaA-A is at a, the focus of the 'parbola BB is at. 7),. and the focus' of the intermediate parabola CC is at 0, all lying in the axis of rojection and also in the axis candescentlamp isstraight and is positioned atthe axis With its illuminating part extending from one limiting focus a to the other b,-thereby containing the foci of all the parabolas forming the rflecting surface. All the light rays wh1ch emanate from a and strike the parabola AA are projected axially therefrom, as are all those which emanate from any other point of the filament -and strike that parabolic curve of the refiecting surface Which has its focus at the point of emanation. In this way,. an intense cylindrical beam is projected axially of the lamp. These axially-directed rays are indicated in Fig. 1 by broken fines.

. The rays which strike the reflecting surface at a parabolic curve not having its focus at the point of emanation are protjected in divergent fines, angularly disposed to the axis of the lamp, those directed downwardly illuminiating the road. Further more, those rays which proceed forwardly from the filament, without striking the reflecting surface, are mostly divergent, but

owing to the fact that the filament 9 ishorizontal, their number is comparatively small. I. have found that this arrangement results in a projection which is composed of an intense cylinder of light axially directed, and of such an amount of difiused light, that the road is nicely illumihated and at a suitable distance ahead of the vehicle. It Will be observed that the base of the lamp is of elliptical form with the'major axis capable of such disposition that the headlight may be nicely accommodated on an automobile.

Having thus described my invention, what I claim is:

1. In a projection lamp, a refiectin surface made up of curves Which are di erent along the intersection with planes containing the axis of projection and Which have a plurality of foci, and a light giving medium containing said foci. 1

2. In a. projection lamp, a reflecting surface made 1ip of parabolas which, at the intersection with different planes containing the axis of projection, have diferent focal lengths, and a light giving medium containing the foci of said parabolas.

3. In a projection lamp,.a refiecting sur face in the form of an elliptic paraboloid, and a light giving medium containihg the foci of the parabolas in said surface.

In testimony whereof I aflix 'my signature, in presence of twowitnesses.

JAMES MYRVEN N'AL.

Witnesses GEORGE F. KUEHN, A. E. BROWN.. 

